Modern heat exchangers are often made of aluminum or aluminum alloy, at least in their core and header portions. Aluminum heat exchangers often use plastic end tanks or manifolds that are mechanically assembled by a bending or crimping process. The crimp most often consists of a deformation on the header tabs that produces an interference with the plastic tanks. This allows the assembly of the header plus the end tank in a way to produce a hermetically sealed or hermetic system by compressing a rubber seal (gasket) in this area to form a seal. By assembly in this manner, the heat exchanger is able to stay sealed and support even elevated internal pressures during the operation of the heat exchanger. Examples of prior art heat exchangers are found in U.S. Pat. No. 4,461,348 Jul. 24, 1984, Toge et al, with FIGS. 1-4 showing the crimped ‘hooks’, tank feet and header positioning in radiators.
Aluminum braze processes used in the production of heat exchangers have many advantages, but also have the disadvantage that the strength gained during the cold (non thermally-heated) work of the header is lost due to the re-crystallization of micro structures during the brazing. Material gets a normalization status.
In order to resist the stresses produced by the pressure, thicker materials have been used. However, these thicker materials mean a significantly negative impact from both a cost and a crimping process point of view.
Generally, conventional radiators for automotive engines are composed of a core unit having metallic tubes and corrugated fins connected with each other by welding in a heat transmitting manner, and an upper and a lower core plate or header connected to both ends of the tubes. Each of the core plates or headers is formed with a holding groove along its periphery.